The present invention relates to a welding-, cutting-, or heating torch with a torch head provided with an outlet nozzle or outlet nozzles and a torch body connecting the torch head with a torch housing and provided with feed passages therethrough, whereby at least part of the torch body and the torch head is flown through by a cooling medium for convective heat transmission.
The modern use of such torches and especially welding torches for hand or machine operation leads to increased temperatures in the region of the torch head nozzles. This is especially the case during so-called protective gas welding, since the thermal loading of the torch head increases during use of protective gases, especially by use of nozzle gases, such as argon or helium.
In known torches of the above-mentioned kind, it has been tried to cool the torch head, and especially the thermally highly loaded nozzle zone thereof, exclusively by cooling media under use of convective heat transmission. However, it has been recognized that the known cooling systems operating strictly with convective heat transmission have the basic disadvantage that only a relatively small temperature drop is possible at a heat transport over longer distances or that large amounts of cooling media with a high flow speed are necessary.
It has been further suggested (see U.S. Pat. No. 4,109,131) to arrange a hermetically sealed heat transmission system between the thermally highly loaded region of the torch head and a region of the torch body which is circumcirculated and/or flowed through by the cooling medium. The heat transmission system contains a heat transporting medium with an automatic heat transport between its heat receiving and its heat releasing zone. At least the heat releasing zone is circumcirculated or flowed through by the cooling medium. With such a heat transmitting system it is possible to transmit the heat developed at the torch head over a relatively short transmitting distance and with high speed to the region of the torch which is flowed-through by the cooling medium, whereafter the thus-transmitted heat is transported away by the cooling medium. The cooling system of the torch is thus divided in a primary system, consisting of the heat transmitting system and a secondary system with convective heat removal, whereby in practice an extremely active thermal cooling of the torch head is obtained. A protective gas may be used for complete cooling, so that additional systems for the cooling medium of the convective heat transmission with their disadvantages may be dispensed with. A considerable simplification of the torch construction is thereby obtained, in addition to the aforementioned efficient cooling of the torch head.
During operation of the torch, especially during welding or cutting by the latter, fumes develop at the region of the torch head. Obviously, the fumes significantly impair the working conditions for an operator or even make these conditions dangerous for the operator's health.
In German Offenlegungsschrift No. 2,217,770 it has been suggested to provide the torch head with circumferential channels surrounding the outlet nozzle for removing the fumes through these channels. For this purpose, the torch is provided with a separate arrangement for removing these fumes by suction from the torch head. The suction arrangement includes conduits for a suction medium, which extend over the entire length of the torch. Obviously, the suction medium and the suction-medium conduits become subjected to comparatively high thermal loads. Moreover, the suction arrangement requires, besides the conduits, additional pipe connections, corresponding connecting elements, etc., which considerably complicate on the one hand the construction of the torch in general and on the other hand the manipulations with such a torch. It is to be also mentioned that such a suction arrangement substantially increases the cost of the torch.